class Square {
    area : number;
    length : number;
    getarea () : number {
        this.area = this.length + this.length;
        return this.area;
    }
    setlength (value : number) : void {
        this.length = value;
    }
}
let s : Square = new Square ();
s.setlength (6);
console.log (s.getarea ());
